Functional Supramolecular Polymers: A Fluorescent Microfibrous Network in a Supramolecular Hydrogel for High‐Contrast Live Cell‐Material Imaging in 3D Environments

Abstract

A new bottom-up strategy based on aromatic peptide amphiphile is developed for a high-contrast visualization of 3D live cell-material imaging-something that has been difficult to achieve previously because of the problems associated with the diffraction of light by the nanosized peptide materials and the aggregation-caused quenching of aggregated π-conjugated fluorophores in the nanostructures. This study reports an example of a novel supramolecular hydrogelator, naphthaleneimide-phenylalanine (NI-Phe), which forms a self-supporting hydrogel displaying a unique microfibrous network and promising aggregation-induced emission characteristics at pH 7.4. The storage modulus of the NI-Phe gel supports the mass of a cell for 3D cell culturing. This work illustrates a new dopant-free supramolecular approach, complementary to well-established doping procedures that should facilitate the development of live cell imaging in 3D scaffolding materials.

Self‐Assembly of an Amino Acid Derivative into an Antimicrobial Hydrogel Biomaterial

“…[2d, 6] In particular, the use of an aphthaleneimide N-cap led to fluorescent fibrils,w hich could be used for imaging purposes. [7] Alternatively,p yrene was successfully applied to obtain at ryptophan-based gel in phosphate buffer at neutralp Hf or encapsulationo fb iomolecules. [8] Alkyl-chain Nacylationsh ave also been explored, althoughp rediction of the supramolecular behavior of these derivativesi sf ar from trivial.…”

“…Different examples have been described to date, with fluorenylmethyloxycarbonyl (Fmoc) being the most popular appendage, followed by naphthalene . In particular, the use of a naphthaleneimide N‐cap led to fluorescent fibrils, which could be used for imaging purposes . Alternatively, pyrene was successfully applied to obtain a tryptophan‐based gel in phosphate buffer at neutral pH for encapsulation of biomolecules .…”

Enzyme Instructed Self‐assembly of Naphthalimide‐dipeptide: Spontaneous Transformation from Nanosphere to Nanotubular Structures that Induces Hydrogelation

“…For example, Tao Yi and coworkers have studied gelation behaviors of NI compounds and they found that materials displayed high fluorescence quantum yields in both solution and solid‐state . Recently we reported a NI‐based supramolecular hydrogelator, which exhibits AIE phenomenon . Particularly, we have shown the self‐assembly of NI−F that results in the formation of AIE‐active microfibers which facilitate the high contrast visualization of 3D live cell imaging .…”

“…Supramolecular hydrogels of many reported peptide molecules self-assembled into nanofibrillar morphology with the smallest possible width size, which is much less than 50 nm. [27] Few examples of higher-order self-assembled aggregates are also known in the literature. [19,38,39] Understanding the selfassembly mechanism for the formation of such large aggregates is of significant importance but remains challenging.…”

Injectable Supramolecular Hydrogel/Microgel Composites for Therapeutic Delivery

“…Examples of supramolecular chemistry include molecular self‐assembly, host–guest complexes, and mechanically interlocked molecular structures . Supramolecular hydrogels have been used in a variety of biomedical applications, including but not limited to imaging, tissue engineering, and therapeutic delivery . The injectable nature of supramolecular hydrogels makes them particularly attractive for clinical translation since they can be delivered using minimally invasive approaches.…”